Programmable start-of-sector pulse generator for a disk drive using embedded servo bursts and split data fields

Abstract

A disk drive system employs uniform size data blocks, with each disk having a sectorized track format and each sector of a track including at least one servo burst. Data blocks exhibit a constant data density across a plurality of disk tracks of differing radii. The system comprises read/write apparatus for accessing both servo signals and data signals in each disk sector. A servo system is responsive to servo signals fed from the read/write apparatus to generate a synchronizing signal. A data sector pulse generation circuit is responsive to the synchronizing signal to generate and pass to the read/write apparatus, a data sector pulse for each block of data commencing in a sector. That data sector pulse enables operation of the read/write apparatus upon the data block. A control circuit enables the delay of generation of a next data sector pulse when any block of data is split by a servo burst. The delay period is the duration of the servo burst and the portion of the data block that follows the servo burst.

What is claimed is: 
     
       1. A disk drive system employing uniform size data blocks, a disk in said disk drive system having a sectorized format, each sector including at least one servo burst, each said data block exhibiting a constant data density across a plurality of disk tracks of differing radii, said system comprising: read/write means for accessing both servo signals and data signals in each disk sector;   servo means responsive to servo signals fed from said read/write means for generating a synchronizing signal;   data sector pulse generating means responsive to said synchronizing signal to provide to said read/write means, a start of data sector pulse for each block of data commencing in a data sector and including means for enabling the generation of a next start of data sector pulse when any block of data is split by a servo burst, said next start of data sector pulse generated after the duration of said servo burst and the duration of a partial data block that follows said servo burst.   
     
     
       2. The disk drive system as recited in claim 1 wherein said read/write means is responsive to a start of data sector pulse to either read or write a data block. 
     
     
       3. The disk drive system as recited in claim 1, further comprising: memory means for storing for a sector, a first value corresponding to a time length of a data block portion in said sector, said data block split by a servo burst and a second value corresponding to a number of data blocks that start in said sector, said data sector pulse generating means responsive to said stored values to enable generation of start of data sector pulses in said sector.   
     
     
       4. The disk drive system as recited in claim 3, further comprising: processor means responsive to a received data block address to cause said read/write means to access a disk track that includes an addressed data block and to further cause a read-out from said memory means of stored first and second values for a track and sector containing said addressed data block.   
     
     
       5. The disk drive system as recited in claim 4 wherein said data sector pulse generating means further comprises: a data block length register for receiving a value corresponding to a time length of a full data block in an identified disk track;   a start of data sector pulse counter for receiving said second value from said memory means for a sector in said identified disk track;   a data sector length register for receiving said first value for a split data block at the commencement of said data sector in said identified data track; and   a data sector length counter that is set to the value of said data sector length register if said value is non-zero and if said value is equal to zero, to the first value from said data block length register; and   means for causing said data sector length counter to count down to zero to enable the generation of a start of data sector pulse.   
     
     
       6. The disk drive system as recited in claim 5 wherein said data sector pulse generating means further comprises: a state machine responsive to a zero count from said data sector length counter to generate said start of data sector pulse.   
     
     
       7. The disk drive system as recited in claim 6 wherein said data sector pulse generating means further comprises: multiplexer means responsive to an output from said state machine to control the value loaded into said data sector length counter.